multimedia/ffmpegthumbnailer: Update 2.2.3 => 2.3.0, take maintainership

Changelog:
https://github.com/dirkvdb/ffmpegthumbnailer/blob/v2.3.0/ChangeLog

Port changes:

• Upstream switched to 'v' version suffix so add it.
• New release contains the remote patch already so remove it.
• Upstream switched to c++14 standart from 11.
• Add new build option similar to current one.
• Remove USES=pathfix.
• Fix warnings from portclippy.

PR: 291861